How to use the voila.app.Voila.launch_instance function in voila

with io.open(fd, 'w', encoding='utf-8') as fh:
            # TODO: do we want to have the token?
            # if self.token:
            #     url = url_concat(url, {'token': self.token})
            url = url_path_join(self.connection_url, uri)

            jinja2_env = self.app.settings['jinja2_env']
            template = jinja2_env.get_template('browser-open.html')
            fh.write(template.render(open_url=url, base_url=url))

        def target():
            return browser.open(urljoin('file:', pathname2url(open_file)), new=self.webbrowser_open_new)
        threading.Thread(target=target).start()


main = Voila.launch_instance